1. Field of the Invention
This invention relates to an improved piston and cylinder type thermal device, a self-contained lubricant storage and applying means therefor and to methods of making the same.
2. Prior Art Statement
It is known to provide a piston and cylinder type thermal device having a cylinder member carrying a piston stem that has an outer end that projects out of an opening of an end of the cylinder member to be extended and retracted relative thereto upon changes of sensed temperature of a charge of material disposed in the cylinder member that operatively acts on a resilient stem seat disposed in a cylinder member and having an opening in one end thereof that receives an inner end of the stem therein, the stem having a lubricant thereon to tend to prevent abrasion between the stem and the seat during the extended and retracted movements therebetween. For example, see the U.S. patent to Wagner, U.S. Pat. No. 3,046,787 and the U.S. patent to Sliger, U.S. Pat. No. 3,719,085.
Also, see the U.S. patent to Sliger, U.S. Pat. No. 4,095,470 which, in addition to the above structure, has a seal member at the end of the cylinder member to scrape contaminants from the outer end of the stem to prevent the contaminants from entering into the cylinder member during the extending and retracting movement of the stem relative to the cylinder member.
It is also known to provide porous washer-like members impregnated with a lubricant and held in a rigid annular fixed housing for sealing against a reciprocating valve stem passing therethrough. For example see the U.S. patent to Day et al, U.S. Pat. No. 3,762,384.